I read a recent comment to a YouTube video that theorized Bungie meant to give the Bad Juju, The Thorns exotic ability, and to give The Thorn, Bad Juju's exotic ability. The Thorn would instantly recharge ammo after a kill (which is why the incredibly slow reload speed would be okay), and the Bad JuJu would do damage over time (which could explain the small magazine, although it would still probably need a larger one)
Obviously Bungie did what they did intentionally, but I just thought I'd throw that theory out there to see what other players thought if it. Do you think the could actually be called Exotics with swapped abilities?